FNG here. Never done an automatic before...Have built drag cars from tubing to on the track, crewed on A/Fuel dragster, and AA/FA, have my own Altered

[G. Anderson]

I have a 1991 Chev. Suburban, 3/4 ton,
2WD with a 454 and 4L80e transmission.
All totally stock.
Trans is tired .
I will be rebuilding a new to the truck 4L80e.

I want to update the transmission to the newer (post 1996)
style.

Question is WHAT year 4L80e are the best for all automatic shifting,
upgraded for towing once in a while, upgrades for the internals.

Also, and I think most important,
just what do I have to do to the 1991 wiring to get it to
play nicely with the later model (1997 and up) transmission?

Thank yo!

Your Pal, Gary

 

[Will L.]

Welcome Gary. You sound like a fun guy to hang out with! My go fast days went away fast, long ago.

There’s a few guys here with great trans knowledge.

I just know enough to avoid them. Haha

 

[MrMarty51]

Yeah, what He said /\ .
Welcome to the forum G. Anderson.
There was a shop teacher at the high school over here, His name was Fred Anderson. He had a drag racer car, A T-Bucket affair looking thing, the name on the side of it was Aggravation. LOL

 

[G. Anderson]

Thank you for the kind welcome!

Your Pal, Gary

 

[THEFERMANATOR]

1st, you need to look at the 4l80e in generations. 91-93 for all purposes is it's own trans. There are several differences in 91-93 vs 94+. Then you have 94-96, which looks like the 91-93, but uses the 94+ valve body. Then you have the 97+ center lube style. Most pro builders stick with a 96- to build, or at the minimum use the overdrive roller clutch out of a 91-00. The ONLY advantage to a 97+ trans is you can add in the sonnax kit to engage the over run clutches in 1st to 3rd while the shifter is in 4th(this is useful for snow plowing or if you frequently get on and off the throttle, and shift from reverse to drive alot).

IF you're dead set on going to a 97+ style, you should also add in 3/8" or 1/2" trans cooler lines and a later model radiator with the higher flowing cooler as the 97+ needs ALOT more cooler flow than a 91-96. At the absolute least you have to adapt your 5/16" lines over to the 97+ style hook-ups(and make certain to use the 4l80e SPECIFIC fittings). Next you have 3 choices, you either re-use your 91-93 style valve body and add in the accumulator housing from it to the 97+ valve body and drill the extra passages, upgrade to a 7427 ECM with a custom tune(the 7427 was used in 94/95, but 94/95 7.4's had high pressure injection vs the low pressure injection of 93 and older 7.4 tbi's, so custom tuning is required, or you have to change the fuel pump, injectors, pressure regulator spring, and I believe add in a 2nd knock sensor), or go with a stand alone trans controller.

Personally I would stick with your 91 trans, rebuild it with borg warner high energy frictions(stock frictions for late model 4l80e's), heavy duty intermediate snap ring, all new bushings, internally dual feed the direct clutch, use the sonnax boost valve with internal bypass spring, transgo actuator feed limit valve, rollerize the output shaft, rollerize the forward hub, transgo or sonnax tcc valve with a sealing ring, new electrical, converter with a billet piston, new style internal & external harnesses if not already done, and a HUGE external trans cooler(LONG makes a nice one for $130 on Amazon). I'm sure I'm forgetting a few things, but there are TONS of write-ups out there on 4l80e builds and proven build combos.

 

[MrMarty51]

1st, you need to look at the 4l80e in generations. 91-93 for all purposes is it's own trans. There are several differences in 91-93 vs 94+. Then you have 94-96, which looks like the 91-93, but uses the 94+ valve body. Then you have the 97+ center lube style. Most pro builders stick with a 96- to build, or at the minimum use the overdrive roller clutch out of a 91-00. The ONLY advantage to a 97+ trans is you can add in the sonnax kit to engage the over run clutches in 1st to 3rd while the shifter is in 4th(this is useful for snow plowing or if you frequently get on and off the throttle, and shift from reverse to drive alot).

IF you're dead set on going to a 97+ style, you should also add in 3/8" or 1/2" trans cooler lines and a later model radiator with the higher flowing cooler as the 97+ needs ALOT more cooler flow than a 91-96. At the absolute least you have to adapt your 5/16" lines over to the 97+ style hook-ups(and make certain to use the 4l80e SPECIFIC fittings). Next you have 3 choices, you either re-use your 91-93 style valve body and add in the accumulator housing from it to the 97+ valve body and drill the extra passages, upgrade to a 7427 ECM with a custom tune(the 7427 was used in 94/95, but 94/95 7.4's had high pressure injection vs the low pressure injection of 93 and older 7.4 tbi's, so custom tuning is required, or you have to change the fuel pump, injectors, pressure regulator spring, and I believe add in a 2nd knock sensor), or go with a stand alone trans controller.

Personally I would stick with your 91 trans, rebuild it with borg warner high energy frictions(stock frictions for late model 4l80e's), heavy duty intermediate snap ring, all new bushings, internally dual feed the direct clutch, use the sonnax boost valve with internal bypass spring, transgo actuator feed limit valve, rollerize the output shaft, rollerize the forward hub, transgo or sonnax tcc valve with a sealing ring, new electrical, converter with a billet piston, new style internal & external harnesses if not already done, and a HUGE external trans cooler(LONG makes a nice one for $130 on Amazon). I'm sure I'm forgetting a few things, but there are TONS of write-ups out there on 4l80e builds and proven build combos.

I now know where I will be sending My transmission should it ever need a going through. LOL

 

[G. Anderson]

1st, you need to look at the 4l80e in generations. 91-93 for all purposes is it's own trans. There are several differences in 91-93 vs 94+. Then you have 94-96, which looks like the 91-93, but uses the 94+ valve body. Then you have the 97+ center lube style. Most pro builders stick with a 96- to build, or at the minimum use the overdrive roller clutch out of a 91-00. The ONLY advantage to a 97+ trans is you can add in the sonnax kit to engage the over run clutches in 1st to 3rd while the shifter is in 4th(this is useful for snow plowing or if you frequently get on and off the throttle, and shift from reverse to drive alot).

IF you're dead set on going to a 97+ style, you should also add in 3/8" or 1/2" trans cooler lines and a later model radiator with the higher flowing cooler as the 97+ needs ALOT more cooler flow than a 91-96. At the absolute least you have to adapt your 5/16" lines over to the 97+ style hook-ups(and make certain to use the 4l80e SPECIFIC fittings). Next you have 3 choices, you either re-use your 91-93 style valve body and add in the accumulator housing from it to the 97+ valve body and drill the extra passages, upgrade to a 7427 ECM with a custom tune(the 7427 was used in 94/95, but 94/95 7.4's had high pressure injection vs the low pressure injection of 93 and older 7.4 tbi's, so custom tuning is required, or you have to change the fuel pump, injectors, pressure regulator spring, and I believe add in a 2nd knock sensor), or go with a stand alone trans controller.

Personally I would stick with your 91 trans, rebuild it with borg warner high energy frictions(stock frictions for late model 4l80e's), heavy duty intermediate snap ring, all new bushings, internally dual feed the direct clutch, use the sonnax boost valve with internal bypass spring, transgo actuator feed limit valve, rollerize the output shaft, rollerize the forward hub, transgo or sonnax tcc valve with a sealing ring, new electrical, converter with a billet piston, new style internal & external harnesses if not already done, and a HUGE external trans cooler(LONG makes a nice one for $130 on Amazon). I'm sure I'm forgetting a few things, but there are TONS of write-ups out there on 4l80e builds and proven build combos.

Thank you so much for the insights!

I just received the ATSG books on the 4L80e.
VERY impressed with all the information,
pictures and schematics!

I was more than likely going to use the 1991 trans
and just build it for slightly heavier duty use.
Pick and choose on the hard parts...
I think I have viewed most of the 4L80e builds on YouTube!

The '91 2wd Suburban already has a LARGE plate and tube cooler.
Also the Dually.

I have a 1986 Crew Cab Dually, 2wd, 454, etc for heavy towing
(40 foot gooseneck Chapparral race car trailer).

Your Pal, Gary

 

[THEFERMANATOR]

The stock cooler is not that good really. GM used the same 11x6 cooler on all the autos. This cooler has very good reviews and is a much better design over the stock tow cooler. It's made by the same company, but is an improved design(shorter wider coolers flow more evenly than the tall coolers do, GM did this in 06 with the 6 speed allison).

The 47391

Tru-Cool Max. Twice the Cooling for Your Transmission. Maximum Protection for Your Vehicle. | Tru-Cool

When an auxiliary transmission oil cooler is required for your vehicle, Tru-Cool Max delivers optimal protection with double the cooling performance of our other products. Maintain lower temperatures in your transmission and lubricant with Tru-Cool and extend the life of the vehicle you depend on.

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